ABSTRACT
OBJECTIVE: To establish a method for simultaneous determination of 15 kinds of vapor state organic acids in workplace air by solvent desorption-gas chromatography.METHODS: A total 15 kinds of vapor state organic acids such as acetic acid, propanoic acid, butyric acid and pentanoic acid in the air of workplace were collected by silica gel, eluted with acetone, separated by DB-FFAP capillary chromatograph column, and detected by gas chromatography with flame ionization detection. RESULTS: There was a good linear relationship in the selected range of 15 kinds of organic acids. The coefficient correlation was 0.999 97-0.999 98. The limit of detection of this method was 0.04-0.29 mg/L, and the minimum detection concentration was 0.03-0.19 mg/m~(3 )(collected sample volume was 1.50 L). The average desorption efficiency was 92.9%-98.5%. The within-run and between-run relative standard deviation was 0.3%-1.6% and 1.5%-3.0%, respectively. The samples could be kept for at least 15 days at room temperature. CONCLUSION: The method is simple for operation, with high sensitivity, and good precision, which is suitable for simultaneous determination of 15 kinds of vapor state organic acids in the air of workplace and sites of emergency accident.
ABSTRACT
The paraventricular nucleus of the thalamus (PVT), which serves as a hub, receives dense projections from the medial prefrontal cortex (mPFC) and projects to the lateral division of central amygdala (CeL). The infralimbic (IL) cortex plays a crucial role in encoding and recalling fear extinction memory. Here, we found that neurons in the PVT and IL were strongly activated during fear extinction retrieval. Silencing PVT neurons inhibited extinction retrieval at recent time point (24 h after extinction), while activating them promoted extinction retrieval at remote time point (7 d after extinction), suggesting a critical role of the PVT in extinction retrieval. In the mPFC-PVT circuit, projections from IL rather than prelimbic cortex to the PVT were dominant, and disrupting the IL-PVT projection suppressed extinction retrieval. Moreover, the axons of PVT neurons preferentially projected to the CeL. Silencing the PVT-CeL circuit also suppressed extinction retrieval. Together, our findings reveal a new neural circuit for fear extinction retrieval outside the classical IL-amygdala circuit.
ABSTRACT
Cerebral arterial stenosis is a major cause of stroke and of insufficient blood supply to the vertebral basilar system. Percutaneous transluminal cerebral angioplasty and stenting [PTCAS] have been used to preliminarily treat vertebrobasilar stenosis. However, the feasibility to treat the posterior cerebral arterial stenosis by PTCAS has not been fully established. We report a case of a 64-year-old man with a severe stenosis of the posterior cerebral artery that was treated successfully using a PTCAS procedure
ABSTRACT
<p><b>OBJECTIVE</b>TO establish a RP-HPLC method for the determination of calycosin-7-O-beta-D-glucopyranoside in Radix Astragali, and to analyse the calycosin-7-O-beta-D-glucopyranoside content of ten samples of Radix Astragali, collected from different regions.</p><p><b>METHOD</b>A Polaris C18(250 mm x 4.6 mm, 5 microns) column was used and a mixture of methanol-water (30:70) was used as the mobile phase at a flow rate of 1.0 mL.min-1. The column temperature was 25 degrees C and the UV detection wavelength was 254 nm.</p><p><b>RESULT</b>The calibration curve was in good linearity over the range of 0.0106-2.12 micrograms with the regression equation Y = 3035. 97 X - 14.85(r = 0.9999). The average recovery was 95.8% (n = 5, RSD = 1.3%).</p><p><b>CONCLUSION</b>The method is simple, quick, sensitive and reproducible. In all of the samples, the calycosin-7-O-beta-D-glucopyranoside contents differ markedly.</p>